# How to get edges for Conflicts, Assignments, Custom Max Papers, and more

If you want to get all edges for any type of Edge Invitation you can use the [`get_grouped_edges`](https://github.com/openreview/openreview-py/blob/faf9e0c94886150101b709407491f3c431f302ce/openreview/api/client.py#L1718) API call. The most common edges to retrieve are Conflicts, Assignments and Custom Max Papers.

`get_grouped_edges` requires at least 2 fields:

* [**Invitation**](https://docs.openreview.net/reference/api-v2/entities/invitation): The ID of the Edge Invitation.
* **Groupby**: The field of the [Edge](https://docs.openreview.net/reference/api-v2/entities/edge) you want to group the edges by. Typically you will group by the edge's `head` or `tail`.  The value of head and tail are determined by their Invitation. You can view the invitation by going to: `https://openreview.net/invitation/edit?id=invitation_id`

`get_grouped_edges` will return list of dictionaries each containing 2 keys: `id` and `values`. The `id` will contain the field you grouped by and `values` will contain all the edges in that group. The edges are in JSON format.

## Getting all Conflict Edges for the Reviewers Group

This is an example of how to use `get_grouped_edges` to retrieve Reviewer Conflict edges. You can use this method to get any type of Edge.

### Mapping reviewer IDs to their conflict edges

1. Get the conflict invitation ID for the API call:

Get the venue group. The content of the venue group contains many settings for your venue including invitation IDs. The Reviewer Conflict invitation ID is stored as `reviewers_conflict_id` in the content. It follows the format: `venue_id/reviewers_name/-/Conflict`.

```python
venue_group = client.get_group(venue_id)
conflict_invitation_id = venue_group.content['reviewers_conflict_id']['value']
```

2. Get the edges using `get_grouped_edges`:

Call `get_grouped_edges`, pass the invitation ID, and group by the `tail`. Conflict edges are configured so that the `head` is the paper ID and the `tail` is the user with the conflict. When you group by the `head` you can access all the conflicts for a specific paper. Alternatively, if you group by the `tail`, you can access all conflicts for a specific user:

```python
grouped_edges = client.get_grouped_edges(
    invitation = conflict_invitation_id,
    groupby = 'tail'
)
```

3. Map each reviewer profile ID with their conflict edges:

```python
rev_conflict_map =  { group['id']['tail']: group['values'] for group in grouped_edges }
```

### Mapping paper IDs to their conflict edges

If you want to see all conflicts for a specific paper, group by the head instead.

```python
grouped_edges = client.get_grouped_edges(
    invitation = conflict_invitation_id,
    groupby = 'head'
)

paper_conflict_map =  { group['id']['head']: group['values'] for group in grouped_edges }
```

## How to get other types of edges

You can use the same method to get any type of Edge by simply changing the invitation ID. For example:

* To get all Reviewer Assignment edges, pass the Assignment invitation ID:

```python
assignment_invitation_id = venue_group.content['reviewers_assignment_id']['value']
```

* To get all Reviewer Custom Max Paper edges, pass the Custom Max Papers invitation ID:

```python
custom_max_papers_invitation_id = venue_group.content['reviewers_custom_max_papers_id']['value']
```

* To get all Reviewer Affinity Score edges, pass the Affinity Score invitation ID:

```python
affinity_score_invitation_id = venue_group.content['reviewers_affinity_score_id']['value']
```

* To get all Reviewer Bid edges, pass the Bid invitation ID. The full ID isn't stored in the venue group content, so you must build the string using the reviewer ID and bid name:

```python
reviewers_id = venue_group.content['reviewers_id']['value']
bid_name = venue_group.content['bid_name']['value']
bid_invitation_id = f'{reviewers_id}/-/{bid_name}'
```

To get the corresponding invitation IDs for Area Chairs or Senior Area Chairs, just replace `reviewers` with `area_chairs` or `senior_area_chairs`. For example, `area_chairs_assignment_id` or `senior_area_chairs_assignment_id`. If your venue uses other role names, those names will automatically get replaced in the invitation IDs.

## Optional parameters and other use cases

It may be helpful to pass other parameters like `label` and `select` to `get_grouped_edges` to further filter the edges.

### Using `label` to map reviewer IDs to their proposed assignments

Some Edge Invitations allow for edges to be posted with a `label`. To know if this is possible, you have to examine the invitation and see if `label` is configured. If so, you may pass `label='Some label'` to `get_grouped_edges` to retrieve only a subset of those edges.

This is often used when retrieving Proposed Assignment edges. The matcher will post these edges where the label is the title of the matching configuration:

```python
proposed_assignment_invitation_id = venue_group.content['reviewers_proposed_assignment_id']['value']

grouped_edges = client.get_grouped_edges(
    invitation = proposed_assignment_invitation_id,
    groupby = 'tail',
    label = 'rev-matching-1'
)

rev_proposed_assignment_map =  { group['id']['tail']: group['values'] for group in grouped_edges }
```

### Using `select` to map reviewer IDs to their assignment count

You can pass `select = 'count'` to get the number of edges for each grouped entity. In this case, we will group by the user ID with `tail` so that we can map them to their assignment counts. 

```python
grouped_edges = client.get_grouped_edges(
    invitation = assignment_invitation_id,
    groupby = 'tail',
    select = 'count'
)

rev_assignment_count_map =  { group['id']['tail']: group['count'] for group in grouped_edges }
```

{% hint style="info" %}
Notice how `group['values']` changed to `group['count']` in the mapping. This happens only when we select the count.
{% endhint %}

You may also select specific field(s) of the Edge if you don't need to retrieve all the data in the edges. For example, you may pass `select='head,tail'` if you only want to see the head and tail of the edge.